marathon barrier, we need to start at the beginning.

ATHLETE SELECTIONTo identify the runners most likely to run under two hours in the marathon,

three primary factors that help predict performance:
Exercise Capacity:an athlete’s maximum capacity for exercise, expressed as VO2 Max, or the

maximum rate of oxygen consumed.
Running Economy:how much energy a runner needs to run a kilometre at a given speed.
Sustainable Velocity:the speed a runner can sustain for a long period of time without needing

to slow down.
Of the athletes initially screened, three emerged as the most promising: Eliud

At the first team camp, the science team introduced hydration and nutrition strategies,

which have been regularly adjusted month by month. Skin temperatures and sweat

and race day apparel were obsessed over.
And the closer we get to the attempt, the more important temperature becomes for our team.
For the success of Breaking2, the most important temperature reading is the difference

between the body’s internal core temperature and skin temperature. This is known as

the temperature gradient.
"We’re looking at what core body temperature does in relation to skin temperature and

we want those two numbers to be as far apart as possible", Brad Wilkins Director of the

NXT Generation Research team in the Nike Sports Research Lab said. "That means that

the gradient, the temperature gradient, from the core to your skin is really high".
In order to maintain a high temperature gradient for each runner, the team is focusing on